'It's definitely, truly a miracle,' Sarah Thistlethwaite says

An Ohio middle school math teacher was given an early Mother's Day present, giving birth to rare monoamniotic twin girls after spending nearly two months in the hospital.

Sarah Thistlethwaite, from Orrville, Ohio, gave birth to the identical twins, Jenna and Jillian, on Friday. The girls, who were born holding hands, shared an amniotic sac and placenta — a rare occurrence that doctors say happens just once in every 10,000 pregnancies.

Thistlethwaite had been hospitalized at Akron General Medical Center since March 14 after discovering the unborn twins' "mono mono" condition. While in the hospital, Thistlewaite was hooked up to fetal monitors for 20 hours a day.

"When twins share an amniotic sack, there are many risks to monitor," the hospital explained in a blog post. "The twins’ umbilical cords can become entangled or compressed. And there’s a risk that one fetus’ cord might wrap around the other one’s neck."

“Sarah was given the option to deliver between 32 and 34 weeks gestation,” Melissa Mancuso, the doctor who performed the surgery, explained. “This type of twin is at high risk for stillbirth because of cord entanglement. We were just having a discussion about how difficult a decision it is to make, weighing the risk of prematurity versus the risks of entanglement. She was excited about having her C-section on May 9 because she would be a ‘real mother’ on Mothers’ Day.”

The procedure went smoothly, according to the hospital, with Jenna and Jillian weighing 4 pounds, 2 ounces and 3 pounds, 12 ounces, respectively. Because they were considered premature, the twins were taken directly to the hospital's neonatal intensive care unit, where they're expected to spend two to four weeks before they’re ready to go home.